by Gary Mihoces, USA TODAY Sports

by Gary Mihoces, USA TODAY Sports

CLIFTON, Va. -- Washington Redskins quarterback Robert Griffin III returned to limited practice Wednesday, three days after suffering a concussion. Hours later, NFL Commissioner Roger Goodell told youth football parents that Griffin's return to live action still will depend on a "progression" of evaluations.

Goodell was here to watch safe tackling drills by members of the Southwestern Youth Association Wildcats, who are participating this season in a pilot program called Heads Up Football. The program was devised by USA Football, a youth organization endowed by the NFL and the NFL Players Association.

There was a question-and-answer session afterwards with parents in the stands at Centreville High School. One mother, whose son recently sustained a concussion, asked about the evaluation process for returning to play.

"You're seeing it with RGIII," Goodell said. "We use the term progression. ... You want to see how they respond at every step. How do they deal with just sitting in a room with light? Then how do they deal with a room where there's more activity and then maybe more physical activity? At every step you have to pass that progression, and if you do successfully, you're more likely to be successfully recovering from the injury.''

Pittsburgh Steelers linebacker James Harrison said that during another NFL game Sunday he pulled up on one play rather than trying to sack Philadelphia Eagles quarterback Michael Vick., whose deep pass was incomplete.

"I was nervous," Harrison told the Pittsburgh Post-Gazette. "I thought he might duck his head, I might hit him. I can't take (a) fine. I was worried more about a fine.''

Harrison has been fined multiple times by the league for hits deemed illegal. In 2011, he was suspended for a game after a helmet-to-helmet hit on Cleveland Browns quarterback Colt McCoy. Whatever Harrison's motivation on Sunday, Goodell took his remarks as a positive sign.

"That's what's happening, I think," Goodell said. "By the emphasis on the rules, coaches and players have to adjust their techniques. And they proved that they can do that, and they've done that effectively and can still play at a very high level. That's what we're talking about when we say the game has to change -- certain aspects and those techniques and the culture."

Changing the culture at the youth level is the goal of Heads Up Football.

"One of the things you're seeing out on the field here tonight is keeping the head up and keeping the head out of the game. Those are things we stress at all levels," Goodell said.